Underlying causes for bad breath can be many ,such as
-Gum disease which can still exist even after brushing ,tongue cleaning ,just sometimes a little professional help is needed ,that's all!
-Certain types of foods and drinks like onion ,garlic ,coffee .alcohol etc ,can linger in the mouth for a long time and lead to undesirable smell.
-Digestive issues like constipation ,irritable bowel ,acid reflux .
-Dry Mouth
-Food wedging due to partially erupted wisdom teeth.
-Sinus and respiratory infections.
Next Steps
Schedule a dental evaluation for professional clean ,if still persists ,visit a general practitioner
Health Tips
Rinse mouth after every meal